What Is a Flywheel Used for?

Flywheels are exceedingly common devices, yet are often poorly understood. While they are simple in their overall design, they are integral to the smooth operation of a wide variety of mechanical and electrical devices.

Definition

A flywheel is a disc or spoked wheel that spins around a central shaft as a means of storing energy. Flywheels are designed to minimize friction (and in some cases air resistance) to avoid losing energy as the wheel spins for long periods of time.

Mechanical Uses

Flywheels are frequently used in mechanical devices to smooth out movements that come in rapid or uneven bursts. For example, pottery wheels that are driven by foot pedals use flywheels to keep the table rotating at a constant speed using the pulsing energy from the pedal. Auto manufacturers use flywheels in this same manner to even out the power an engine provides.

Electrical Uses

A flywheel connected to an electric motor can store electrical energy as kinetic energy, acting as a battery. The motor drives the flywheel, which can later drive the motor as a generator. Flywheel batteries carry an advantage over traditional chemical batteries in that they have much longer operational lifespans and do not lose their ability to hold a charge except by breaking.

Limitations

A flywheel is limited in the amount of energy it can store by the materials it is made of. If a flywheel spins too fast for its materials, it will shatter from the centrifugal force it generates. Flywheels are also difficult to scale up or down effectively, since their mass affects their ability to receive and store energy, limiting their potential applications.